Soy sauce, or shoyu is one of the most traditional and popular condiments in Japanese cuisine. In the United States, it is getting popularity even in the culinary scenes outside of Asian foods. As opposed to its name ‘soy sauce’, traditional Japanese soy sauce is made from half soybeans and half wheat, which means that the soy sauce is made from a mixture of usually 50% soy and 50% wheat. This composition of the ingredients makes it difficult for gluten intolerant people to enjoy the adorable taste of soy sauce. There are currently over two million people in the United States who are intolerant to gluten. It is sad that they cannot enjoy the savory taste of soy sauce.
There is one kind of soy sauce in Japan, which is called tamari-shoyu in Japanese,—tamari soy sauce translated into English. Tamari soy sauce is distinct from popular standard soy sauce in that little or no wheat is used for its production. Particularly the one that contains no wheat is suitable to serve to the gluten intolerant people to have them enjoy the traditional Japanese taste.
Traditionally, whole soybeans have been used to produce the tamari soy sauce. However, because of the high price of soybean, it is not easy to provide the tamari soy sauce to the consumers with a reasonable price. Therefore, an alternative approach is necessary to provide a reasonable price of tamari soy sauce. One choice for this is to use a processed soybean such as defatted soybean as an ingredient. However, the inventors found it difficult to produce the tamari soy sauce from the defatted soybean.
To produce the tamari soy sauce, it is necessary to form the steamed soybeans into a nugget shape, which is called misodama in Japanese. However, the defatted soybean could not be shaped into the nugget. When a small amount of wheat flour or barley flour was added to the defatted soybean, the shapability of the soybean was greatly improved. However, this approach would not lead the inventors to achieve their goal that is to provide a tamari soy sauce to gluten intolerant people with a reasonable price.
Soy sauce including tamari soy sauce generally contains lots of salt. Lately, there are a lot of health-oriented people, and some of them have demanded a tamari-soy sauce that contains a lower amount of salt. Vacuum concentration is an old-fashioned way of reducing the salt content in the soy sauce. However, the inventors have observed that the vacuum concentration reduces savory flavors of the tamari soy sauce. Lately, electrodialysis is becoming popular to reduce the salt content of soy sauce. However, the inventors disappointedly found that the desalinization by electrodialysis also decreases the thick and deep taste of tamari soy sauce.
To produce the tamari soy sauce, it is necessary to ferment the soy nuggets. In this process, the soy nuggets are put into salt water. There, the soy nuggets float on the salt water instead of sinking in the salt water. There is also an occasion in which not much salt water is added in the tank so that the height of the salt water is lower than the heights of the soy nuggets. Therefore, some portion of the soy nugget is usually exposed in the air, and this portion dries as time goes by. To prevent this, traditionally a craftsman has manually poured the salt water onto the soy nugget. This process is called kumikake in Japanese. However, this work is not practical for the mass production of tamari soy sauce. Therefore, an efficient alternative approach is necessary.